Shelters for crustaceans such as lobsters are well-known in the art. They attract crustaceans during the off-seasons as breeding places. The crustaceans are attracted to dark shelters by day as much as they are by food at night. All year round they provide protection against predators for small and large lobsters, and during the off-seasons they serve as breeding grounds. However, conventional shelters have the serious drawbacks that they are not impervious to light and sound and hence do not constitute attractive shelters, and that, to harvest the sheltered crustaceans, it is necessary for fishermen to risk their lives by diving.
As for conventional traps, these have the ecological drawback that, if they become loosened from their floats, the crustaceans resident therein continue to attract other crustaceans, all of these eventually dying of starvation, until the trap decays.